I’m not actually sure it has a solution that isn’t centralised - where you have some kind of pre-registration (maybe KYC, but blinded after) - and then maybe vote anonymisation (if blind voting). Keep in mind double voting isn’t technically just the same identity voting twice (we could detect duplicate reactions from the same pubkey for example), but also someone creating two+ identities and voting a second time. If you have a closed community of voters, you could perhaps manually share a secret or something - and a double vote would be obvious when you count the people who can vote is less than total votes - at least one fraud vote. I’m kind of glad anyway, as paper ballots are significantly harder to commit fraud with. Any digital government electronic voting is extremely dangerous and should be rejected as an option. I could be missing something that may exist.